Microstructure and Wear Properties of (TiC, TiB)/Ti-6Al-4V Surface-Alloyed Materials Fabricated by High-Energy Electron Beam Irradiation

摘要

The present study is concerned with the microstructural analysis and the evaluation of hardness and wear properties of (TiC,TiB)/Ti-6Al-4V surface-alloyed materials fabricated by high-energy electron beam irradiation. The mixtures of Ti+C, TiC +TiB_2, and Ti+B_4C powders and CaF_2 flux were deposited on a Ti-6Al-4V substrate, and then electron beam was irradiated on these mixtures using an electron beam accelerator. The surface-alloyed layers of 0.9 approx 1.6 mm in thickness were formed without defects, and contained a large amount (30 approx 44 vol. percent) of precipitates such as TiC and TiB in the martensitic matrix. This microstructural modification including the formation of hard precipitates and hardened matrix in the surface-alloyed layers resulted in the improvement hardness and wear resistance. Particularly in the surface-alloyed material fabricated with Ti+B_4C powders, the wear resistance was greatly enhanced by nine times higher than that of the Ti alloy substrate because a 44 vol. percent of TiB and TiC was precipitated homogeneously in the martensitic matrix. These findings suggested that the surface-alloying using high-energy electron beam irradiation was useful for the development of titanium-base surface-alloyed materials with increased surface hardness and improved wear properties.